Power aware techniques for energy harvesting remote sensor system

ABSTRACT

A distributed monitoring system for monitoring one or more operating conditions of a structure includes: one or more sensor nodes coupled to the structure, each sensor node including: a power supply adapted to scavenge energy directed at the power supply; a sensor operably coupled to the power supply for sensing one or more operating conditions of the structure in the environment; and a communications interface operably coupled to the power supply and the sensor for communicating the sensed operating conditions of the structure; a communication network operably coupled to the sensor nodes; one or more controllers operably coupled to the communication network for monitoring the sensor nodes; and an energy radiator positioned proximate the structure adapted to radiate energy at the power supplies of the sensor nodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to patent application Ser. No.12/208,222, filed on Sep. 10, 2008, the disclosure of which isincorporated by reference.

BACKGROUND

This disclosure relates to distributed monitoring systems for astructure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an exemplary embodiment of an aircraftmonitoring system.

FIG. 2 is a schematic illustration of the aircraft monitoring system ofFIG. 1.

FIG. 3 is a schematic illustration of an exemplary embodiment of sensornodes of the aircraft monitoring system of FIG. 2.

FIGS. 4 a and 4 b are flow chart illustrations of an exemplaryembodiment of a method of operating the sensor nodes of FIG. 3.

FIGS. 5 a and 5 b are flow chart illustrations of an exemplaryembodiment of a method of operating the sensor nodes of FIG. 3.

FIG. 6 is a schematic illustration of an exemplary embodiment of anaircraft monitoring system.

FIG. 7 is a schematic illustration of an exemplary embodiment of anaircraft monitoring system.

FIG. 8 is a flow chart illustration of a method of operating an aircraftmonitoring system.

FIG. 9 is a schematic illustration of an exemplary embodiment of anaircraft monitoring system.

FIG. 10 is a flow chart illustration of an exemplary embodiment of amethod of operating an aircraft monitoring system.

FIG. 11 is a flow chart illustration of an exemplary embodiment of amethod of operating an aircraft monitoring system.

FIG. 12 is a graphical illustration of an exemplary embodiment of asensor of a sensor node that includes one or more stable operatingstates.

FIG. 13 is a schematic illustration of an exemplary embodiment of anaircraft monitoring system.

DETAILED DESCRIPTION

In the drawings and description that follows, like parts are markedthroughout the specification and drawings with the same referencenumerals, respectively. The drawings are not necessarily to scale.Certain features of the invention may be shown exaggerated in scale orin somewhat schematic form and some details of conventional elements maynot be shown in the interest of clarity and conciseness. The presentinvention is susceptible to embodiments of different forms. Specificembodiments are described in detail and are shown in the drawings, withthe understanding that the present disclosure is to be considered anexemplification of the principles of the invention, and is not intendedto limit the invention to that illustrated and described herein. It isto be fully recognized that the different teachings of the embodimentsdiscussed below may be employed separately or in any suitablecombination to produce desired results. The various characteristicsmentioned above, as well as other features and characteristics describedin more detail below, will be readily apparent to those skilled in theart upon reading the following detailed description of the embodiments,and by referring to the accompanying drawings.

Referring to FIGS. 1-3, an exemplary embodiment of a system 100 formonitoring an aircraft includes one or more sensors nodes 102 that areoperably coupled to a central controller 104 by a network 106. In anexemplary embodiment, the sensor nodes 102 are distributed within anaircraft 108 for monitoring one or more operational states of theaircraft that may, for example, include stresses, strains, temperatures,and pressures. In an exemplary embodiment, one or more of the sensornodes 102 communicate the operational states of the aircraft 108 to thecentral controller 106 that is housed within the aircraft using, forexample, a network 106 that may, for example, include a hard wired,fiber optic, infra red, radio frequency, packet data, acoustic, or othercommunication pathway.

In an exemplary embodiment, each sensor node 102 includes a power supply102 a that is adapted to scavenge energy from the immediate environment.In an exemplary embodiment, the power supply 102 a may, for example,scavenge electromagnetic energy, solar energy, radio-frequency energy,vibrational energy, heat energy, wind energy, radiated electromagneticand/or other forms of energy from the environment. In an exemplaryembodiment, the power supply 102 a further includes a rechargeablebattery 102 aa operably coupled thereto. In this manner, short bursts ofenergy that may be scavenged can be scavenged by the power supply 102 aand stored for later use in the battery 102 aa. In an exemplaryembodiment, the power supply 102 a is operably coupled, and suppliespower, to a communication link 102 b, a switch 102 c, a micro-controller102 d, a signal conditioner 102 e, a sensor 102 f, a switch 102 g, aswitch 102 h, and a memory 102 i.

In an exemplary embodiment, the communication link 102 b is alsooperably coupled to the switch 102 c and adapted to transmit and receivecommunication signals between the sensor node 102 and the network 106.In this manner, the sensor node 102 may communicate with other sensornodes and the central controller 104.

In an exemplary embodiment, the switch 102 c is also operably coupled tothe communication link 102 b and the micro-controller 102 d and adaptedto be controlled by the micro-controller to thereby communicationsbetween the communication link and the micro-controller. In this manner,in the event that the micro-controller 102 d determines thatcommunication should not occur between the communication link 102 b andthe micro-controller such as, for example, if the sensor node 102 lackssufficient power, the micro-controller may operate the switch to preventcommunication between the communication link and the micro-controller.

In an exemplary embodiment, the micro-controller 102 d is also operablycoupled to the communication link 102 b, the switch 102 c, the signalconditioner 102 e, the sensor 102 f, and the switch 102 g for monitoringand controlling the operation of each. In an exemplary embodiment, themicro-controller 102 d may include, for example, a conventional generalpurpose programmable controller.

In an exemplary embodiment, the signal conditioner 102 e is alsooperably coupled to the micro-controller 102 d and the sensor 102 andadapted to condition signals transmitted by the sensor before they arefurther processed by the micro-controller. In an exemplary embodiment,the signal conditioner 102 e may, for example, include one or moreconventional signal processing elements such as, for example, filters,amplifiers, and analog to digital converters.

In an exemplary embodiment, the sensor 102 f is also operably coupled tothe signal conditioner 102 e and the switch 102 g and adapted to senseone or more operating conditions of the aircraft 108 in the immediateenvironment. In an exemplary embodiment, the sensor 102 f may include,for example, one or more of the following: a strain gauge, a stresssensor, a temperature gauge, a pressure gauge, a radiation detector, aradar detector, a chemical sensor, a corrosion sensor and/or a detectorof electromagnetic energy.

In an exemplary embodiment, the switch 102 g is also operably coupled tothe micro-controller 102 d and the sensor 102 f and adapted to controlthe operation of the sensor under the controller of themicro-controller. In this manner, in the event that the micro-controller102 d determines that the sensor 102 f should not operate such as, forexample, if the sensor node 102 lacks sufficient power, themicro-controller may operate the switch 102 g to prevent power frombeing supplied by the power supply 102 a to the sensor.

In an exemplary embodiment, the switch 102 h is also operably coupled tothe micro-controller 102 d and the communication link 102 b and adaptedto control the operation of the communication link under the controllerof the micro-controller. In this manner, in the event that themicro-controller 102 d determines that the communication link 102 bshould not operate such as, for example, if the sensor node 102 lackssufficient power, the micro-controller may operate the switch 102 h toprevent power from being supplied by the power supply 102 a to thecommunication link.

In an exemplary embodiment, the memory 102 i is also coupled to themicro-controller 102 d in order to store the operating system of thesensor node 102 as well as other operating parameters and measurementstaken by the sensor 102 f. The memory 102 i may, for example, includeone or more conventional memory devices such as, for example, DRAMS,Flash memory, optical storage, hard disk drive, or other memory devices.In an exemplary embodiment, the memory 102 i is adapted to store atleast one of the mechanical, electrical, chemical, bistable, ormulti-stable states of the sensor 102 f.

Referring now to FIGS. 4 a and 4 b, in an exemplary embodiment, one ormore of the sensor nodes 102 of the system 100 implement a method 400 ofoperating in which, in 402, the sensor node determines if there is anypower available to the sensor node. If there is any power available tothe sensor node 102, then the sensor node determines if there is enoughpower available to the sensor node to permit the sensor node to executeat least one operation in 404.

If there is enough power available to permit the sensor node 102 toexecute at least one operation, then the sensor gets a listing of thepossible operations given the amount of available power in 406. Thesensor node 102 then gets a listing of the current and next operationalstates for the sensor node in 408.

The sensor node 102 then determines if the next operational states ofthe sensor node are included in the possible operations given the amountof available power in 410. If the next operational states of the sensornode 102 are included in the possible operations given the amount ofavailable power, then the sensor node executes the next operationalstates that are possible to execute given the amount of available powerin 412.

Referring now to FIGS. 5 a and 5 b, in an exemplary embodiment, one ormore of the sensor nodes 102 of the system 100 implement a method 500 ofoperating in which, in 502, the sensor node determines if there is anypower available to the sensor node. If there is any power available tothe sensor node 102, then the sensor node determines if there is enoughpower available to the sensor node to permit the sensor node to executeat least one operation in 504.

If there is enough power available to permit the sensor node 102 toexecute at least one operation, then the sensor gets a listing of thepossible operations given the amount of available power in 506. Thesensor node 102 then gets a listing of the current and next operationalstates for the sensor node in 508.

The sensor node 102 then determines if the next operational states ofthe sensor node are included in the possible operations given the amountof available power in 510. If the next operational states of the sensornode 102 are included in the possible operations given the amount ofavailable power, then the sensor node executes the next operationalstates, based upon their pre-determined priority, that are possible toexecute given the amount of available power in 512.

Referring now to FIG. 6, an exemplary embodiment of a system 600 formonitoring an aircraft is substantially identical in design andoperation as the system 100 with the addition of a power dispenser andconditioner 602 that is operably coupled to a source of raw power 604, apower manager 606, a power allocator 608.

In an exemplary embodiment, the source of raw power 608 may include oneor more of the power supplies 102 a of one or more of the sensor nodes102. In an exemplary embodiment, the power dispenser and conditioner 602is adapted to receive time varying raw power, P(t)_(raw), from thesource of raw power 604, condition the raw power, and then transmit timevarying available power, P(t)_(avail), to the power allocator 608. In anexemplary embodiment, the power dispenser and conditioner 602 includesone or more elements for conditioning the raw power such as, forexample, a rectifier, a filter, and a regulator.

In an exemplary embodiment, the power manager 606 includes a powermonitor 606 a and a power controller 606 b. In an exemplary embodiment,the power monitor 606 a is operably coupled to the output of the powerdispenser and conditioner 602 for monitoring the available power,P(t)_(avail). In an exemplary embodiment, the power monitor 606 a isalso operably coupled to the power controller 606 b for communicatingthe available power, P(t)_(avail), to the power controller. In anexemplary embodiment, the power controller 606 b is also operablycoupled to the power allocator 608 for controlling the operation of thepower allocator.

In an exemplary embodiment, the power allocator 608 includes one or moreallocators 608 i that are each coupled to one or more elements of thesensor node 102 for controllably supplying power to the correspondingelements of the sensor node. In this manner, the power manager 606 andthe power allocator 608 collectively determine the power available tothe sensor node 102 and then allocate the available power to theelements of the sensor node.

In an exemplary embodiment, the system 600 may implement one or moreaspects of the methods 400 and 500, described and illustrated above withreference to FIGS. 4 a, 4 b, 5 a, and 5 b. In an exemplary embodiment,the elements and functionality of the power dispenser and conditioner602, the raw power source 604, the power manager 606, and the powerallocator 608 may be provided within one or more of the sensor nodes 102and/or provided within the central controller 104.

Referring now to FIG. 7, an exemplary embodiment of a system 700 formonitoring an aircraft is substantially identical in design andoperation as the system 600 except that the power allocator 608 isomitted and the functionality formerly provided by the power allocatoris provided by the micro-controller 102 d within the sensor nodes 102.

In particular, in the system 700, the power controller 606 b is operablycoupled to the micro-controller 102 d of the sensor node 102 fordirecting the allocation of the available power by the micro-controllerto the elements of the sensor node.

In an exemplary embodiment, the system 700 may implement one or moreaspects of the methods 400 and 500, described and illustrated above withreference to FIGS. 4 a, 4 b, 5 a, and 5 b. In an exemplary embodiment,the elements and functionality of the power dispenser and conditioner602, the raw power source 604, and the power manager 606 may be providedwithin one or more of the sensor nodes 102 and/or provided within thecentral controller 104.

Referring now to FIG. 8, in an exemplary embodiment, one or more of thesystems 100, 600, and 700 may implement a method 800 of operating inwhich, in 802, the sensor nodes 102 are placed into a default mode ofoperation which may, for example, include a sleep mode in which thesensor node is inactive, a fully active mode in which the sensor node isfully active, or one or more intermediate active modes in which thesensor node has functionality that is less than in the fully activemode. In 804, the system, 100, 600, or 700, will then determine theamount of power available to the system. In an exemplary embodiment, in806, the system, 100, 600, or 700, will then determine the availableoperational states of the sensor nodes 102 of the system given theamount of power available to the system.

In an exemplary embodiment, in 808, the system, 100, 600, or 700, willthen determine the quality of the possible monitoring of the aircraft108 given the available operational states of the sensor nodes 102 ofthe system given the amount of power available to the system. In anexemplary embodiment, the quality of the possible monitoring of theaircraft 108 may be a function of what monitoring is adequate based uponthe operating envelope and actual operating condition of the aircraft.For example, when the aircraft 108 is cruising at high altitudes withminimal turbulence, the level of detail and sampling rate in themonitored conditions may be less than when the aircraft is climbing to,or diving from, altitude with heavy turbulence.

In an exemplary embodiment, in 810, the system, 100, 600, or 700, willthen modify the operational states of the sensor nodes 102 in order tooptimize one or more of: 1) the available operational states of thesensor nodes, 2) the volume of data collected by the sensor nodes, 3)the sampling rate of the data collected by the sensor nodes, 4) thecommunication throughput of data within the network 106, and/or 5) thequality of the possible monitoring.

In an exemplary embodiment, during the operation of the systems, 100,600 and/or 700, the switches, 102 c, 102 g and 102 h, may be operated bythe micro-controller 102 d to place the sensor node 102 in a sleep modeby not permitting operation of the communication link 102 b and thesensor 102 f. In this manner, the use of power by the sensor node 102 isminimized.

In an exemplary embodiment, during the operation of the systems, 100,600 and/or 700, the sensor node 102 may be operated in a sleep mode ofoperation that may, for example, include a range of sleeping mode thatmay vary from a deep sleep to a light sleep. In an exemplary embodiment,in a deep sleep mode of operation, the sensor node 102 may be completelyasleep and then may be awakened by a watch dog timer, externalinterrupt, or other alert. In an exemplary embodiment, in a light sleepmode of operation, some of the functionality of the sensor node 102 maybe reduced. In an exemplary embodiment, in one or more intermediatesleeping modes of operation, the functionality of the sensor node 102will range from a light sleep to a deep sleep.

In an exemplary embodiment, in one or more of the systems 100, 600 and700, one or more of the elements and functionality of the powerdispenser and conditioner 602, the raw power source 604, the powermanager 606, and the power allocator 608 may be provided within a sensornode 102, within one or more groups of sensor nodes, and/or within thecentral controller 104.

In an exemplary embodiment, in one or more of the systems, 100, 600 and700, one or more of the elements and functionality of the raw powersource 604 may be provided within a single sensor node 102, within oneor more groups of sensor nodes, or by all of the sensor nodes. Forexample, if the power supply 102 a in each of the sensor nodes 102within one of the systems, 100, 600 or 700, is a solar cell, then thelevel of solar energy at each sensor node 102 will vary as a function ofits location on the aircraft 108. In an exemplary embodiment, theallocation of power within the sensor nodes 102 of the systems, 100, 600and 700, will determine the mapping of the power generated by the sensornodes and then allocate power among the sensor nodes in order tooptimize the operation of the systems in monitoring the aircraft 108.

In an exemplary embodiment, in one or more of the systems 100, 600 and700, one or more of the sensor nodes 102 may provide one or more of theelements and functionality of the central controller 104.

In an exemplary embodiment, one or more of the systems 100, 600 and 700,may be operated to provide an optimal quality of the possible monitoringof the aircraft 108 by placing one or more determined sensor nodes 102into a sleep mode, even in the presence of adequate power to operate thedetermined sensor nodes if the systems determine that the optimalquality of the possible monitoring of the aircraft can still beachieved. In this manner, the determined sensor nodes 102 placed into asleep mode may do one or more of: store power or store data within thedetermined sensor node. In this manner, data may be warehoused within asensor node 102 for later use and/or power may be stored within thesensor node for later use.

In an exemplary embodiment, one or more of the systems 100, 600 and 700,may be operated to place one or more determined sensor nodes 102 into asleep mode if the data for the determined sensor node may beextrapolated using the data available for adjacent sensor nodes.

Referring now to FIG. 9, an exemplary embodiment of a system 900 formonitoring an aircraft is substantially identical in design andoperation as the system 100 except that an energy radiator 902 ispositioned proximate the aircraft 108 and a central controller 904 isoperably coupled to the network 106.

In an exemplary embodiment, the energy radiator 902 includes one or moreradiators of energy such as, for example, electromagnetic energy, solarenergy, radio-frequency energy, vibrational energy, heat energy, and/orwind energy. In this manner, the energy radiator 902 may permit thepower supplies 102 a of the sensor nodes 102 to scavenge energy foroperating the sensor nodes from the energy radiated by the energyradiator 902.

In an exemplary embodiment, the central controller 904 is operablycoupled to the network 106 in order to monitor and control the operationof the sensor nodes 102. In an exemplary embodiment, the centralcontroller 904 may include a plurality of central controllers positionedproximate the aircraft 100.

Referring to FIG. 10, in an exemplary embodiment, the system 900implements a method 1000 of monitoring an aircraft in which, in 1002,selected ones of the sensor nodes 102 are radiated with energy byoperating the energy radiator 902. In an exemplary embodiment, theamount of energy radiated in 1002 is selected to provide at least athreshold level of energy that may be scavenged by the selected sensornodes 102 thereby permitting a predetermined level of desiredfunctionality to be achieved by the sensor nodes.

In 1004, the selected ones of the sensor nodes 102 scavenge the radiatedenergy using the power supplies 102. In an exemplary embodiment, atleast some of the scavenged radiated power is stored in a power storagebattery provided in at least some of the power supplies. In this manner,a relatively short burst of radiated energy may provide functionality ofthe selected sensors nodes 102 for an extended period of time.

In an exemplary embodiment, the method 1000 is implemented as part of astatic test of the aircraft 108 while the aircraft is housed within ahangar.

In an exemplary embodiment, the energy radiator 902 may radiateelectromagnetic energy using a planar wave whose energy level does notdecay substantially with distance. In an exemplary embodiment, theenergy radiator 902 may include a phased array antenna for radiatingenergy. In an exemplary embodiment, the energy radiator 902 may includean arbitrarily large antenna and/or one or more directional antennas.

In an exemplary embodiment, the energy radiator 902 may radiate a largeenough pulse of energy such that the batteries 102 aa of the powersupplies 102 of the sensor nodes 102 are fully charged such thatcontinued static testing of the aircraft 108 may continue with orwithout the need for further radiation of energy to the sensor nodes.

In an exemplary embodiment, the energy radiator 902 may include a lightsource operably coupled to a leaky fiber optic cable or light pipe thatis positioned proximate the sensor nodes 102 to which it is desired toradiate energy. In an exemplary embodiment, the energy radiator 902 mayinclude a source of thermal energy that may create temperature gradientswithin the aircraft 108 that may be used by the power supplies 102 a ofthe sensor nodes 102 to generate energy.

In an exemplary embodiment, the energy radiated by the energy radiator902 is selected to include forms of energy that will not effect thestructure and/or the measurements to be taken of the aircraft 100.

Referring to FIG. 11, in an exemplary embodiment, the system 100implements a method 1100 of monitoring an aircraft in which, in 1102,the sensor nodes 102 scavenge sufficient energy from the localenvironment to permit the sensors 102 f of the sensor nodes to sense oneor more operating conditions and store the measured operating conditionwithin the sensor and/or the memory 102 i. In an exemplary embodiment,in 1102, the sensors 102 f of the sensor nodes 102 recognize that athreshold measured value has been obtained and thereby latch to thatsensed value

In an exemplary embodiment, as illustrated in FIG. 12, the sensors 102 fof the sensor nodes 102 are provided with one or more stable operatingstates that are each reflective of a value of an operating condition.For example, as illustrated in FIG. 12, one or more of the sensors 102 fof the sensor nodes 102 may include an initial operating state S₀. Uponthe sensing of an operating condition, which would include some form ofinput energy to the sensor 102 f, the operational state may then changeto a stable sensed state S₁. The sensor 102 f of the sensor node 102would remain in this stable latched operational state unless and untilanother event reflective of a change in operating conditions, whichwould include some form of input energy to the sensor 102 f, occurredwhich would move the sensor to a new stable operational state S2. Inthis manner, the sensor 102 f of the sensor 102 would latch onto thesensed operational state and the sensor could be a mechanical latchand/or an electronic latch. In an exemplary embodiment, the number ofstable operational states could be any value and such value coulddetermine the level of granularity in the sensor 102 f. In an exemplaryembodiment, the number of stable operational states also may be used toprovide an electrical and/or mechanical analog to digital converter inwhich the number of stable operational states of the sensor 102 fdetermines the number of levels in the analog to digital converter.

In an exemplary embodiment, the sensors 102 f of one or more of thesensor nodes 102 are further adapted to stored measure values ofoperating conditions using the energy associated with the operatingcondition itself. In this manner, the sensors 102 f are able to storestored measure values of operating conditions using the energyassociated with the operating condition for indefinite periods of time.For example, as illustrated in FIG. 12, the sensor 102 f may include oneor more stable operating states that are each entered into by injectingenergy into the sensor, where the injected energy is the operatingcondition being measured.

In an exemplary embodiment, in 1104, sensor nodes 102 are then radiatedwith energy in sufficient amounts to permit the sensor nodes to transmitthe stored measurements and to reset the sensors 102 f. In an exemplaryembodiment, in 1104, as illustrated in FIG. 13, the sensor nodes 102 areradiated with energy in sufficient amounts to permit the sensor nodes totransmit the stored measurements by operating an energy radiator 1302proximate the sensor nodes. In an exemplary embodiment, the design andoperation of the energy radiator 1302 is substantially the same as theenergy radiator 902.

In an exemplary embodiment, in 1106, the sensor nodes 102 scavenge theradiated energy using the power supplies 102. In an exemplaryembodiment, at least some of the scavenged radiated power is stored in apower storage battery provided in at least some of the power supplies.In this manner, a relatively short burst of radiated energy may providefunctionality of the selected sensors nodes 102 for an extended periodof time. In an exemplary embodiment, in 1106, the sensor nodes 102scavenge the radiated energy using the power supplies 102 in sufficientamount to permit the sensor nodes to transmit the stored measurementsand to reset the sensor 102 f.

In an exemplary embodiment, in 1108, the sensor nodes 102 determinewhether to transmit the stored measurements or, in the alternative, totransmit the stored measurements and then reset the sensor 102 f. In anexemplary embodiment, each sensor 102 will be programmed by a user ofthe system 100 in order to determine which action should be taken.Alternatively, the desired action to be taken may be altered bydownloading instructions to the sensor nodes 102 and/or may beadaptively determined as a function of the type or location of thesensor 102 f of the sensor node, the magnitude of the storedmeasurements, or other factors.

If a particular sensor node 102 has been instructed to only transmit thestored measurements, then, in 1110, the sensor node will only transmitthe stored measurements to one or more of the central controllers 104.In an exemplary embodiment, in 1110, the transmission of the storedmeasurements by the sensor node may be a singlecast or multicasttransmission, and may, for example, be transmitted using data packetsprotocols.

If a particular sensor node 102 has been instructed to transmit thestored measurements and reset the sensor 102 f, then, in 1112, thesensor node will transmit the stored measurements to one or more of thecentral controllers 104 and then the sensor node 102 will then reset theassociated sensor 102 f in 1114. In an exemplary embodiment, in 1112,the transmission of the stored measurements by the sensor node may be asinglecast or multicast transmission, and may, for example, betransmitted using data packets protocols. In an exemplary embodiment, in1114, the sensor 102 node 102 will reset the sensor 102 f by, forexample, resetting the operational state of the sensor to an earlieroperational state.

In an exemplary embodiment, as illustrated in FIG. 13, in 1110 and/or1112, the sensors 102 and/or the central controllers 104 may transmitthe stored measurements to one or more external central controllers1304. In an exemplary embodiment, the energy radiator 1302 may include,or at least be operably coupled to, the central controller 1304. In thismanner, a portable device that may include both the energy radiator 1302and the central controller 1304 may be used to wand over selected sensornodes 102 to thereby interrogate the sensor nodes, capture the storedmeasurements contained therein, and, if required, also reset the sensors102 f in one or more of the selected sensor nodes 102.

In an exemplary embodiment, after completing 1110 and/or 1112, one ormore of the central controllers 104 may send an acknowledgement to thesensor node 102 that transmitted the stored measurements and, in anexemplary embodiment, upon the receipt of the acknowledgement by thesensor node, the sensor node will reset the sensor node's operationalstate.

In an exemplary embodiment, the method 1100 may be used, for example, toprovide a regular diagnostic program for the aircraft 108 by mountingthe energy radiator 1302 and the central controller 1304 at a fixedlocation such as, for example, in the ceiling of an aircraft hangar.Then, as the aircraft 108 is moved into or out of the hangar, the storedmeasurements within the sensors 102 f of the sensor nodes 102 may beextracted for processing by the central controller 1304 to determine thehealth of the aircraft.

In an exemplary embodiment, the method 1100 may be used, for example, toprovide a regular diagnostic program for a carrier based aircraft 108 bymounting the energy radiator 1302 and the central controller 1304 at afixed location such as, for example, the aircraft elevator on thecarrier. Then, as the aircraft 108 is moved onto or off of the deck ofthe carrier, the stored measurements within the sensors 102 f of thesensor nodes 102 may be extracted for processing by the centralcontroller 1304 to determine the health of the carrier based aircraft.

It is understood that variations may be made in the above withoutdeparting from the scope of the invention. For example, the teachings ofthe exemplary embodiments may be applied to monitoring an aircraft, aship, a vehicle, a building, the environment, or any other applicationin which a distributed monitoring system would provide value. Whilespecific embodiments have been shown and described, modifications can bemade by one skilled in the art without departing from the spirit orteaching of this invention. The embodiments as described are exemplaryonly and are not limiting. Many variations and modifications arepossible and are within the scope of the invention. Accordingly, thescope of protection is not limited to the embodiments described, but isonly limited by the claims that follow, the scope of which shall includeall equivalents of the subject matter of the claims.

1. A distributed monitoring system for monitoring one or more operatingconditions of a structure, comprising: one or more sensor nodes coupledto the structure, each sensor node comprising: a power supply adapted toscavenge energy directed at the power supply; a sensor operably coupledto the power supply for sensing one or more operating conditions of thestructure in the environment; and a communications interface operablycoupled to the power supply and the sensor for communicating the sensedoperating conditions of the structure; a communication network operablycoupled to the sensor nodes; one or more controllers operably coupled tothe communication network for monitoring the sensor nodes; and an energyradiator positioned proximate the structure adapted to radiate energy atthe power supplies of the sensor nodes; wherein one or more of thesensor nodes comprise a memory operably coupled to the sensor; andwherein the memory comprises at least one stable latched operationalstate of the sensor.
 2. The system of claim 1, wherein one or more ofthe sensor nodes comprise a rechargeable battery operably coupled to thepower supply.
 3. The system of claim 1, wherein the sensor of one ormore of the sensor nodes comprises at least one stable latched operatingstate representative of a corresponding measurement value of anoperating condition.
 4. The system of claim 3, wherein said stablelatched operating state remains unchanged until reset by one or more ofthe controllers.
 5. The system of claim 3, wherein the sensor of one ormore of the sensor nodes comprises one or more of: an electrical device,a mechanical device, a chemical device, and an electro-mechanicaldevice, that comprises at least one stable latched operating staterepresentative of a corresponding measurement value of an operatingcondition.
 6. The system of claim 3, wherein the sensor of one or moreof the sensor nodes is adapted to change to a stable latched operatingstate of the sensor using energy provided by the operating conditionmeasured by the sensor.
 7. The system of claim 1, wherein the energyradiator and one or more of the controllers are positioned proximate thestructure.
 8. The system of claim 7, wherein the energy radiator and oneor more of the controllers are positioned within a common housing. 9.The system of claim 1, wherein the energy radiator comprises a radiatorof one or more of the following: radiofrequency energy, optical energy,and thermal energy.
 10. The system of claim 1, wherein the structurecomprises an aircraft.
 11. A distributed monitoring system formonitoring one or more operating conditions of a structure, comprising:one or more sensor nodes coupled to the structure, each sensor nodecomprising: a power supply adapted to scavenge energy directed at thepower supply; a sensor operably coupled to the power supply for sensingone or more operating conditions of the structure in the environment;and a communications interface operably coupled to the power supply andthe sensor for communicating the sensed operating conditions of thestructure; a communication network operably coupled to the sensor nodes;one or more controllers operably coupled to the communication networkfor monitoring the sensor nodes; and an energy radiator positionedproximate the structure adapted to radiate energy at the power suppliesof the sensor nodes; wherein the power supply of one or more of thesensor nodes is adapted to scavenge enough directed energy to permit thesensor of the corresponding sensor node to sense one or more operatingconditions and reset an operating state of the sensor of thecorresponding sensor node.
 12. The system of claim 11, wherein the powersupply of one or more of the sensor nodes is adapted to scavenge enoughdirected energy to permit the sensor of the corresponding sensor node tosense one or more operating conditions and provides power to enable toreset an operating state of the sensor of the corresponding sensor nodeas directed by one or more of the controllers.
 13. A method of operatinga system for monitoring one or more operating conditions of a structure,comprising: providing sensor nodes at locations around the structure forsensing operating conditions of the structure; directing radiated energyat one or more of the sensor nodes; scavenging the radiated energy atone or more of the sensor nodes; and using the scavenged energy at oneor more of the sensor nodes to transmit sensed operating conditions fromone or more of the sensor nodes; and using the scavenged energy at oneor more of the sensor nodes to reset an operating condition of a sensorof one or more of the sensor nodes.
 14. The method of claim 13, whereinone or more of the sensor nodes store a measurement of one or moresensed operating conditions.
 15. The method of claim 14, wherein usingthe scavenged energy at one or more of the sensor nodes to transmitsensed operating conditions from one or more of the sensor nodelocations comprises using the scavenged energy at one or more of thesensor nodes to transmit the stored sensed operating conditions.
 16. Themethod of claim 14, wherein using the scavenged energy at one or more ofthe sensor nodes to transmit sensed operating conditions from one ormore of the sensor node locations comprises using the scavenged energyat one or more of the sensor nodes to transmit the stored sensedoperating conditions and reset an operating condition of a sensor of oneor more of the sensor nodes.
 17. The method of claim 13, wherein thestructure comprises an aircraft.
 18. The method of claim 13, wherein oneor more of the sensor nodes use energy associated with the sensedoperating condition to store a measurement of the sensed operatingcondition.
 19. A sensor node for use in a distributed monitoring systemfor monitoring one or more operating conditions of a structure,comprising: a power supply; a sensor operably coupled to the powersupply for sensing one or more operating conditions of the structure inthe immediate environment; a communications interface operably coupledto the power supply and the sensor for communicating the sensedoperating conditions of the structure; and a controller operably coupledto the power supply, the sensor, and the communications interface;wherein the sensor comprises one or more stable latched operating statesthat are each reflective of a corresponding value of one or moreoperating conditions.
 20. The sensor node of claim 19, wherein the powersupply comprises a rechargeable battery for storing energy provided bythe power supply.
 21. The sensor node of claim 20, wherein the sensor isadapted to use energy associated with the sensed operating condition tostore the sensed operating condition.
 22. A distributed monitoringsystem for monitoring one or more operating conditions of a structure,comprising: one or more sensor nodes coupled to the structure, eachsensor node comprising: a power supply adapted to scavenge energydirected at the power supply; a sensor operably coupled to the powersupply for sensing one or more operating conditions of the structure inthe environment; and a communications interface operably coupled to thepower supply and the sensor for communicating the sensed operatingconditions of the structure; a communication network operably coupled tothe sensor nodes; and one or more controllers operably coupled to thecommunication network for monitoring the sensor nodes; wherein one ormore of the sensors comprise at least one stable latched operating staterepresentative of a corresponding measurement value of an operatingcondition.
 23. The system of claim 22, wherein said stable latchedoperating state remains unchanged until reset by one or more of thecontrollers.